A bud is an undeveloped shoot from which embryonic
leaves or flower parts arise. The buds of trees and shrubs of the
temperate zone typically develop a protective outer layer of
small, leathery, bud scales. Annual plants and herbaceous
perennials have naked buds in which the outer leaves are green and
Buds of many plants require exposure to a certain
number of days below a critical temperature (rest) before they
will resume growth in the spring. This time period varies for
different plants. The flower buds of forsythia require a
relatively short rest period and will grow at the first sign of
warm weather. Many peach varieties require 700 to 1,000 hours of
temperatures below 45°F (7°C) before they will resume
growth. During rest, dormant buds can withstand very low
temperatures, but after the rest period is satisfied, buds become
more susceptible to weather conditions and can be damaged easily
by cold temperatures or frost.
A leaf bud is composed of a short stem with
embryonic leaves, with bud primordia in the axils and at the apex.
Such buds develop into leafy shoots. Leaf buds are often less
plump and more pointed than flower buds.
A flower bud is composed of a short stem with
embryonic flower parts. In some cases the flower buds of plants
which produce fruit crops of economic importance are called fruit
buds. This terminology is objectionable because flowers have the
potential for developing into fruit. This development may never
occur because of adverse weather conditions, lack of pollination
or other unfavorable circumstances. The structure is a flower bud
and should be so designated since it may never set fruit.
Types of Buds
Buds are named for the location which they inhabit on the stem
surface. Terminal buds are those which are located at the apex of
a stem. Lateral buds are borne on the sides of the stem. Most
lateral buds arise in the axis of a leaf and are called axillary
buds. In some instances more than one bud is formed. Adventitious
buds are those which arise at sites other than in the terminal or
axillary position. Adventitious buds may develop from the
internode of the stem; at the edge of a leaf blade; from callus
tissue at the cut end of a stem or root; or laterally from the
roots of a plant.
Buds as Food
Enlarged buds or parts of buds form the edible portion of some
horticultural crops. Cabbage and head lettuce are examples of
unusually large terminal buds. Succulent axillary buds of Brussels
sprouts become the edible part of this plant. In the case of globe
artichoke, the fleshy basal portion of the bracts of the flower
bud are eaten along with the solid stem portion of the bud.
Broccoli is the most important horticultural plant in which edible
flower buds are consumed. In this case, portions of the stem as
well as small leaves associated with the flower buds are eaten.